Hardening copper alloys



Patented Oct. 1, 1940 V UNITED STATES 2,216,379 HARDENING COPPER ALLOYS Persak Tookousian, Detroit, Mich., assignor of fifteen per cent to Ha Mich.

rry E. Kouzian, Detroit,

No Drawing. Application November 23, 1938,

Serial No. 241,993 a 4 Claims. (Cl. 148-132) This invention is a continuation in part of my. 1

application Serial No. 72,097, filed April 1, 1936, and relates to the hardening of metals and their alloys and particularly copper alloys.

It is well recognized in metallurgy that-copper and its alloys are far more difiicult to harden than steel and other ferrous alloys. The hardening of steel by quenching at a high heat is old and common practice, now developed to the point of quite accurate regulation. Copper and many of its important alloys have been found nonsusceptible to such a hardening process, such metal being annealed or softened by application of considerable heat and retaining its softness under quenching treatments heretofore practiced.

An object of the invention is to provide a quenching bath and treatment for copper and its alloys, which by reason of dissolution in such bath of certain chemicals in suitable proportions exercise a' material hardening effect.

The chemicals preferably employed in forming my improved quenching solution are sodium carbonate, potassium chloride, and potassium permanganate, approximately equal weights thereof being preferred. Best results have been secured by dissolving approximately one part by Weight of each of said salts in approximately twenty-one parts by weight of water. It is found that efli ciency of such a solution is somewhat increased by addition thereto of concentrated hydrochloric acid approximating one eleventh by volume of the water and that a slight further improvement in the results accrues from adding concentrated nitric acid in a volume approximately equaling that of the hydrochloric acid.

To derive the best results from the described solution, the metal to be hardened is brought to a red heat and then abruptly submerged in the solution, being therein until temperatures of the metal and solution approximfiely equalize. Precooling of the solution is recommended when a maximum hardening effect is desired.

As exemplifying results obtainable with the described solution, reference is made to an alloy, as follows: 7

Parts by weight Copper H 100 Zinc 5 Arsenic 2% Phosphorus Upon quenching such alloy in the described bath, the resultant Brinell hardness was found to lie between one hundred and fifty-seven (157) and one hundred and sixty-one (161), the variation in different specimens being attributed primarily to varying degrees of purity in the constituent metals.

By again bringing the specified alloy to a red will heat and quenching in the same solution, they hardness was further increased by approximately four Brinell degrees. Repeated quenching may be used with a similar beneficial eifect in treating copper and other alloys thereof.

Superiorheat conductivity of the particular solution employed, in conjunction with its pronounced scale-removal properties appears to best explain its special fitness for the purpose disclosed. Scale formation due to the oxidation incident to heat treatment materially retard heat dissipation in employing any ordinary quenching bath, whereas the solution now disclosed exercises a vigorous action in dislodging scale immediately on submergence of the metal, being thus afforded intimate contact with substantially the entire surface of the metal.

It is to be noted in this connection that the softness of ordinary copper unfits it for many uses to which it is otherwise well suited. Hammering, rolling, or other cold working has been commonly employed to increase the hardness but such treatment is relatively expensive. There is consequently a high utility in any provision whereby copper may be materially hardened by quenching, similarly to steel.

The invention is presented as including all such modifications and changes as come within the scope of the following claims.

What I claim is: r

1. The process of hardening a copper alloy consisting in bringing the same to a redheat and abruptly cooling by submergence in a solution whereof the solute comprises substantially equal parts by weight of sodium carbonate, potassium chloride and potassium permanganate.

2. The process of hardening a copper alloy consisting in submerging the alloy, while at a red heat, in a solution comprising approximately one part by weight of sodium carbonate, one part by weight of potassium chloride, one part by weight of potassium permanganate, and twenty-one parts by weight of water.

3. The process of hardening a copper alloy consisting in submerging the alloy, While at a red heat, in a liquid carrying in solution substantially equal parts by weight of sodium carbonate, potassium chloride, and potassium permanganate.

4. A bath for quenching and hardening copper alloys comprising approximately the following ingredients in approximately the stated proportions by weight:

Parts Water 21 Sodium carbonate 1 Potassium chloride 1 Potassium permanganate 1 PERSAK TQOKOUSIAN. 

